Washer for fastener and for fastening of objects

ABSTRACT

A washer to be applied between a nut threadingly connected with a bolt which has an axis and is introduced into an object including two parts to be assembled, the washer has a body having an axis and provided with a first bearing face surface located at one axial side and adapted to cooperate with a nut, a second bearing face surface located at an opposite axial side and adapted to cooperate with the object, and at least one third turning resistant surface adapted to cooperate with a thread of the bolt, so that when the nut is turned with a given torque in one direction and the body of the washer receives simultaneously the given force in an opposite direction, only the nut turns to tighten or loosen the bolt and the body of the washer remains rotation stationary while the bolt elongates or relaxes in an axial direction.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a washer, a fastener providedwith a washer, and a method of fastening with the use of the washer.

[0002] It is known to fasten objects with one another with a fastenerwhich has a multi-part replacement nut, for example including an innersleeve, an outer sleeve, and a washer. Such a replacement nut isdisclosed for example in our U.S. Pat. No. 5,341,560. Anotherreplacement nut is disclosed in our U.S. Pat. No. 6,254,323 in which abolt has a spline underneath its upper thread, to which a washer isnon-rotatably connected, and the bolt also has engaging means forapplying a reaction force, while an active force of the same tool turnsthe nut on the bolt thread and the washer face. In the fastenerdisclosed in both above mentioned patents, the common features are theuse of the action and reaction force of one tool, the elimination ofreaction arms on torque powertools, the conversion of torque totorsion-free bolt stretching and obtaining for the first time thedesired residual bolt load as compared to torque, which is estimatedbased on calculated frictions rather than actual frictions or hydraulictension, which is based on estimated bolt relaxation when the force istransmitted from the elongated bolt to the hand-tight nut.

[0003] The problem found in the industry with the fastener disclosed inU.S. Pat. No. 5,341,560 is that, since the nut has to be made with twosleeves whose outside diameter has to meet the outside diameter of aregular nut, both sleeves have less material than a regular nut. Thisrequires the use of high strength materials, which causes a reluctanceon the part of the customers to change materials and fear of theunknown. In the fastener disclosed in U.S. Pat. No. 6,254,323 the boltneeds to be altered, which is not just costly but not easily acceptableby the industry. In other words the fastener disclosed in our U.S. Pat.No. 5,341,560 requires alteration of the nut, while the fastenerdisclosed in our U.S. Pat. No. 6,254,323 requires alteration of thebolt. In addition, both versions are expensive to produce, adding tocustomer's reluctance to purchase these fasteners.

SUMMARY OF THE INVENTION

[0004] Accordingly, it is an object of the present invention to providea washer, a fastener provided with a washer, and a method of fasteningwith the use of the washer, which avoid the disadvantages of the priorart.

[0005] In keeping with these objects, one feature of present inventionresides, briefly stated, in a washer which has a body having an axis andprovided with a first bearing face surface located at one axial side andadapted to cooperate with a nut, a second bearing face surface locatedat an opposite axial side and adapted to cooperate with an object, andat least one third turning resistant surface adapted to cooperate with athread of the bolt, so that when the nut is turned with said given forcein one direction and said body of the washer receives simultaneouslysaid given force in an opposite direction, only the nut turns to tightenor loosen the bolt and the body of the washer remains rotationstationary, while the bolt elongates or relaxes in an axial direction.

[0006] Another feature of present invention resides in a threadedfastener for connecting two parts which constitute an object, whichfastener has a bolt having a thread; a nut screwable on the bolt; and awasher to be applied between a nut and a bolt and having a body with anaxis and with a first bearing face surface located at one axial side andadapted to cooperate with a nut, a second bearing face surface locatedat an opposite axial side and adapted to cooperate with an object, andat least one third turning resistant surface adapted to cooperate with athread of the bolt, so that when the nut is turned with a given force inone direction and the body of the washer receives simultaneously saidgiven force in an opposite direction, only the nut turns to tighten orloosen the bolt and the body of the washer remains rotation stationary,while the bolt elongates or relaxes in an axial direction.

[0007] Still another feature of the present invention resides in amethod of assembling at least two parts with one another, comprising thesteps of introducing a bolt having a thread into the parts so that afree end of the bolt extends outwardly beyond at least one side of thetwo parts; placing a friction washer on said free end portion of saidbolt so that said friction washer engages with said thread of said boltto create a turning friction between said washer and said bolt and so asto abut against said at least one side of the two parts; threadablyconnecting a nut to said free end portion of said bolt so as to abutagainst the friction washer and to form an assembly; placing a torquepower tool on the assembly so as to tighten or loosen the nut with aturning portion of said torque power tool connected to the nut toovercome a threaded friction between the bolt and a facial friction withthe friction washer to turn the nut, and with a reaction portion of thetorque power tool connected to the washer to absorb a reaction force dueto a facial friction of the friction washer with the nut, a facialfriction of the washer with said at least one side of the two parts anda turning friction of the washer with the bolt selected so that thewasher remains stationary while the bolt elongates or relaxes in anaxial direction.

[0008] Still another feature of the present invention is that the thirdturning resistant surface of the washer increases its turning resistanceand/or its resistance toward an axial movement in use according to theincrease in drag friction created by the nut onto the bolt when it isunder tension, by having the turning resistant surface squeezed furtherinto the bolt thread and against the inside of one of the washer partsas a result of the drag friction of the bolt or the turning forceapplied to the washer if the given force is applied to it in theopposite direction.

[0009] In accordance with another feature of the present invention, theturning resistant portion of the washer has for example a ring having aninward side engaging in the bolt thread and an outward side having gearteeth to turn a gear engaging in the gear teeth of the ring and alsoengaging in the inward side of the washer body with two facial frictionareas. The gear can be connected to a plate between the washer body andthe object. When the bolt turns along with the nut the turning resistantportion of the washer wants to turn along in the same direction, tryingto turn the gear, which in turn tries to turn the washer body in theopposite direction to the drag friction applied to its bearing facesurface by the nut so that the bolt and the washer with its partsremains rotation stationary while the nut is turned.

[0010] The drag friction created by the nut on the bolt can be quitehigh, the nut does in no way diminish the bolt load resulting from thetorque applied to the nut when the bolt stands still. It is the objectof the present invention to use a torque tool's reaction force in a waythat allows the bolt to move in an axial direction when the nut isturned. Therefore, to stop the bolt from turning with or in the thirdturning resistant surface of the washer when the drag friction is high,a wedge can be inserted between the inner surface of the outer washerpart and the outer surface of the inner washer part to increase theturning friction created by the turning resistant surface of the washerwith the bolt.

[0011] The wedge part can but does not have to project above the firstbearing surface. When it does project and the nut is turned down on it,the wedge part moves down and wedges the turning resistant surface intothe bolt thread to stop all turning of the bolt relative to it. When itdoes not project and the turning resistant surface moves up as a resultof the turning of the bolt, the upward movement causes it to be pressedagainst the bolt thread to stop the bolt from turning, in which case itis best located within the two bearing faces of the washer in a way thatit also eliminates turning of the turning resistant surface of onewasher part relative to the other washer part. Therefore when the boltturns along with the nut and the turning resistant surface arises as aresult of it, the turning resistant surface gets squeezed further intothe bolt thread, the bolt stops turning as a result of it and theturning resistant surface rises only with the bolt stretch created bythe turning nut.

[0012] When the washer and the fastener are designed in accordance withthe present invention and the method is performed in accordance with thepresent invention, regular nuts and regular bolts can be used. In otherwords the customer can use whatever he has adding merely a washer. Thebenefit is quite remarkable. First of all the product is much lessexpensive than each of the products in the above mentioned patents.Secondly, the customer uses his approved bolts and nuts. Third, insteadof reacting on a part of the nut directly as in the U.S. Pat. No.5,341,560 or indirectly as in the U.S. Pat. No. 5,946,789 by passing thereaction force through the washer to a part of the nut, the reactionforce is solely absorbed by the washer. Furthermore, the solutionproposed in the present application provides the identical benefits asthe solutions disclosed in the above mentioned patents, one of which isa torsion-free elongation of the free portion of the bolt, a knowncoefficient of friction between the nut face and the washer face andthus a known bolt load precision, a reaction-arm free hydraulic torquetool use, a bridge- and precision puller-free bolt stretching. In otherwords, torque is converted into torsion- and side-load-free boltelongation to the desired bolt load by means of a torque power tool,which can be also applied to torque regular nuts with a reaction member.It needs to be considered that most bolts in the industry are throughbolts with a nut on the other side or blind bolts threaded into thebottom part of the two parts.

[0013] It is known that if a torque power tool is applied to a fastenerin a way where the nut is turned by the active force of the torque powertool and the reaction is absorbed by a regular washer underneath thenut, then either the nut or the washer will turn at will or the boltturns along with the nut and nothing is accomplished, or the bolt endtightens further into the blind hole causing the bottom threads tomushroom which makes disassembly extremely difficult. The reason forthat is that the nut has two friction areas, the threaded connectionwith the bolt which creates a drag friction and the facial area with thewasher, whereby the washer has one facial area with the nut and onefacial area with the two parts to be assembled. In other words, bothhave two friction areas. While it is correct that a threaded friction isa little less than a facial friction, the difference is minute as thefacial friction between the washer and the nut balance each other out,so that there is merely one minute difference between the nut and thewasher. At the same time if the bolt is a through bolt, the threadfriction between the bolt and the nut is such that the bolt turningresistance is much less than the facial friction of the washer and whilethe washer would absorb the reaction force without turning, the boltwould turn along with the nut and nothing is accomplished unless aback-up wrench is used to stop the bottom nut from turning. Therefore,neither is enough to guarantee that only the nut turns, which is why thethird friction area had to be introduced to the washer.

[0014] On the other hand, if the washer is connected with the thread ofthe bolt, the bolt can not turn along with the nut because the washerwill have to lift up which it can not because the nut is on top of it.Bolt elongation resulting from turning down the nut is, therefore,impossible. The present invention therefore provides a bolt threadengaging washer section which is connected with the bolt thread. Thisalone would not help because this section could move either along withthe bolt by rotating or upward if the bolt rotates in it and nothing isaccomplished. This in turn would allow the bolt to turn along with thenut as the section rotates or moves up. Therefore in accordance with afurther new feature of the present invention, the bolt thread engagingmeans is frictionally connected with the body of the washer, so that itsrotational or upward movement is subject to overcoming a frictiongreater than a drag friction created on the bolt by the turning nut, tostop the bolt from turning. This friction in conjunction with the twofacial frictions of the washer assure that the bolt does not move alongwith the nut, that the bolt is stretched, and that the washer and itsbolt thread engaging section do not rotate while the nut is beingturned.

[0015] If the reaction force of the tool is applied to the outside ofthe washer through engagement means thereon, it is also possible to havea pin or the like connected with one end of the thread engagementsection and having its other end sticking out of the circumference ofthe washer so that when the tool is connected with the washer the pin ispushed inwardly pushing the thread engagement section inwardly into thebolt thread.

[0016] The novel features which are considered as characteristic for thepresent invention are set forth in particular in the appended claims.The invention itself, however, both as to its construction and itsmethod of operation, together with additional objects and advantagesthereof, will be best understood from the following description ofspecific embodiments when read in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIGS. 1-6 are views of a threaded fastener provided with a washerin accordance various embodiments of the present invention; and

[0018]FIG. 7 is a view illustrating a fastening process with the use ofthe fastener and the washer in accordance with the present invention,and a torque power tool.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019]FIG. 1 shows a threaded fastener which has a bolt identified withreference numeral 1 and introducible into an object which is composedfor example of two parts to be assembled with one another as identifiedwith reference numeral 2. The fastener further has a nut which isidentified with reference numeral 3. The nut is provided with an innerthread 4 which is screwed on an outer thread 5 of the bolt 1.

[0020] The threaded fastener further has a washer which is identified asa whole with reference numeral 6. The washer 6 has a body identifiedwith reference numeral 7 which is provided with a first upper bearingface surface 8 cooperating with the nut 3, a second lower bearing facesurface 9 cooperating with the object 2 or in particular with a surfaceof one of the parts to be assembled with one another, and at least oneturning resistant surface which is identified with reference numeral 10.The first and second bearing face surfaces are spaced from one anotherin an axial direction or in other words in a direction of an axis A1 ofthe washer which coincides with an axis A2 of the bolt. The at least onethird turning resistant surface 10 is located radially inwardly of thebody 7 of the washer 6. The third turning resistant surface 10 is formedso as to engage with or wedge in the thread 5 of the bolt 1, for exampleby providing a corresponding thread 11 on the turning resistant surface10.

[0021] As shown in FIG. 1, the body 7 is composed of two parts 7′ and 7″which are located radially adjacent to one another, so that the part 7″is located radially inwardly of the part 7′. The turning resistantsurface 10 with the bolt thread engaging means 11 is provided radiallyinwardly on the part 7″. The parts 7′ and 7″ are connected with oneanother so as to avoid turning relative to one another, but to permit amovement relative to one another in an axial direction. For thispurpose, the parts 7′ and 7″ can be frictionally connected with oneanother, for example by being press-fit to create a greater resistancetoward movement than the turning force applied by the bolt and so as tostop the bolt from turning along with the nut and permitting an axialmovement of the part 7″ relative to the part 7′ when the bolt is pulledup by the turning nut.

[0022] In the embodiment shown in FIG. 1a the turning of the part 7″relative to the part 7′ is stopped by interengaging splines 12, forexample provided on the radially outer surface of the part 7″ and theradially inner surface of the part 7′, which permits the axial movementof the part 7″ only.

[0023] In the embodiment shown in FIG. 1b the turning of the part 7″relative to the part 7′ is prevented for example by a key 13 whichpermits axial movement between the parts 7′ and 7″ only.

[0024] As shown in FIG. 2 the part 7″ can be for example formed as asplit ring, and its radially outward surface can have inwardly roundedpockets 14 extending in the axial direction and radially inward surfaceof the part 7′ can contain pins 15 which are coaxial with the bolt axisand which sit partially in the pockets. They force the split ringinwardly into the bolt thread if a turning motion is introduced into thepart 7′ and/or the 7″, while limiting the turning between the parts 7′and 7″ and also adding a further friction to the movement of the part 7′and 7″ relative to one another in the axial direction.

[0025] As shown in FIG. 3 the part 7′ can have an oval inward surfacewhose rounded portion has a given dimension, while the part 7″ can haveat least one ring section engaging the bolt thread and located in therounded portion by another dimension. Therefore the ring section isforced inwardly into the bolt thread if a turning motion is introducedto the part 7′ and/or the part 7″ in either direction, while addingrestrictions to the movement of the part 7′ and the part 7″ relative toone another.

[0026] In accordance with a further embodiment shown in FIG. 3a, thepart 7″ can be other than round or oval. It can have a shape which isdifferent from the round or oval shapes.

[0027] As shown in FIG. 4, the part 7″ can be at least one part whichfor example has one of its sides banking on the inward surface of thepart 7′ and formed to restrict the turning motion of the part 7″. It hasits outer side engaging with the bolt thread and formed with increasingradius relative to the above mentioned one side, so as to turn withinits restrictions and thus engage more and more the bolt thread with itsouter side, while squeezing more and more with its other side againstthe inward surface of the part 7′ to increase its friction with the partrelative to the axial movement of the part 7″.

[0028] In the embodiment of FIG. 4a a pin 16 sits for example on thepart 7 and extends outwardly through the part 7″ to extend beyond theouter circumference of the part 7″. Therefore when the engaging means ofthe tool are connected to the engaging means of the part 7″ the pin 16is pushed inwardly to push the thread engaging section into the boltthread, so that the washer can be placed on the bolt without requiringthe turning of the washer down the extending bolt threads and so thatthe axial movement of the thread engaging section is subject toovercoming the friction between it and the pin 16.

[0029] In the embodiment of FIG. 5 the washer is formed so as to stopthe bolt and the washer from turning along with the nut when the nut isturned by a power tool. Therefore, a turning resistant portion 7″ of thewasher 7 has for example a ring having an inward side engaging in thebolt thread and an outward side having gear teeth to turn a gearengaging in the gear teeth of the ring and also engaging in the inwardside of the washer body with the two facial friction areas. The gear 17is connected to a plate 18 between the washer body and the object. Whenthe bolt turns along with the nut, the turning resistant portion of thewasher wants to turn along in the same direction trying to turn the gearwhich in turn tries to turn the washer body in the opposite direction tothe drag friction applied to its bearing face surface by the nut, sothat the bolt and the washer with its part remains rotation stationarywhile the nut is turned.

[0030] In the embodiment of FIG. 6 the washer is formed so as to stopthe bolt from turning in the turning resistant portion of the part 7″ byproviding at least one wedge-shaped part 18 between the parts 7′ and 7″.It stops the part 7″ from turning in the part 7″ so that the drag forceof the turning bolt can only rise the turning resistant portion of thewasher which, however, wedges it further into the bolt thread until thebolt stops turning and the turning resistant surface moves only axiallywith the bolt.

[0031] When as shown in FIG. 7, a torque power tool 21 is placed on thefastener so as to tighten or loosen the nut 5, a turning portion 22 ofthe torque power tool 21 is connected to the nut 5 and turns the nut toovercome the thread friction with the bolt 1 and the facial frictionwith the washer 6 to turn the nut 5, while a reaction portion 23 of thetorque power tool 21 is connected to the washer 6 to absorb the reactionforce due to the facial friction of the washer 6 with the nut 5, itsfacial friction with one side of the parts 2, and its turning frictionwith the bolt 1, so that the washer 6 and the bolt 1 do not turn, butabsorb the reaction force of the torque power tool.

[0032] It is to be understood that in order to engage the nut 5 by theturning part 22 of the torque power tool 21, the nut must havecorresponding connecting means formed, for example as a polygonal shapeof the outer surface of the nut, as splines provided on the outersurface of the nut, etc. On the other hand, in order to connect thereaction portion 23 of the torque power tool 21 to the washer 6, thewasher also must be provided with connecting means formed for examplealso as a polygonal outer surface of the washer, or as a plurality ofsplines of the outer surface of the washer, etc. as identified withreference numeral 13.

[0033] The lower bearing face surface 9 of the body of the washer can beformed to have a high friction relative to the object, for example,roughened.

[0034] In accordance with the invention it is also possible that thebolt thread engaging means have a different angle than a thread of thebolt, to create a greater friction between it and the bolt thread.

[0035] It is also possible that the bolt thread engaging means is notthreaded, but have a surface softer than a surface of the bolt to causefriction.

[0036] It will be understood that each of the elements described above,or two or more together, may also find a useful application in othertypes of constructions differing from the types described above.

[0037] While the invention has been illustrated and described asembodied in washer, fastener provided with a washer, and method offastening with the use of the washer, it is not intended to be limitedto the details shown, since various modifications and structural changesmay be made without departing in any way from the spirit of the presentinvention.

[0038] Without further analysis, the foregoing will so fully reveal thegist of the present invention that others can, by applying currentknowledge, readily adapt it for various applications without omittingfeatures that, from the standpoint of prior art, fairly constituteessential characteristics of the generic or specific aspects of thisinvention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:
 1. A washer to be applied between anut threadingly connected with a bolt which has an axis and isintroduced into an object including at least two parts to be assembled,the washer comprising a body having an axis and provided with a firstbearing face surface located at one axial side and adapted to cooperatewith the nut, a second bearing face surface located at an opposite axialside and adapted to cooperate with the object, and at least one thirdturning resistant surface adapted to cooperate with a thread of thebolt, so that when the nut is turned with a given force in one directionand said body of the washer receives simultaneously said given force inan opposite direction, only the nut turns to tighten or loosen the boltand said body of the washer remains rotation stationary while said boltelongates or relaxes in an axial direction.
 2. A washer as defined inclaim 1; and further comprising bolt thread engaging means which isformed on said at least one third turning resistant surface of said bodyto engage the thread of the bolt and is frictionally connected with saidbody.
 3. A washer as defined in claim 2, wherein said at least one thirdturning resistant surface is a radially inner surface of said body whichis coaxial with said axis of said body and is provided with said boltthread engaging means.
 4. A washer as defined in claim 2, wherein saidbody is composed of two parts which are arranged radially near oneanother and include a radially inner part and a radially outer part,said bolt thread engaging means being provided on said inner part, saidparts being formed so that they are not freely rotatable relative to oneanother but are axially displacable relative to one another.
 5. A washeras defined in claim 4, wherein said bolt thread engaging means hasthreads having a different angle than a thread of the bolt so as tocreate a greater friction between it and the bolt thread.
 6. A washer asdefined in claim 4, wherein said bolt thread engaging means is notthreaded but has a surface softer than a thread of the bolt to causefriction.
 7. A washer as defined in claim 4; and further comprisingmeans for pressing said bolt thread engaging means to and wedging in thebolt thread during turning of the nut and including inclined surfacemeans provided on one of said parts and acted upon during turning of thenut so as to press said inner part radially in a radially inwarddirection toward the bolt.
 8. A washer as defined in claim 7; andfurther comprising pin means arranged between said parts and acting onsaid inclined surface means to press said inner part in a radiallyinward direction toward the bolt.
 9. A washer as defined in claim 4; andfurther comprising means for connecting said parts with one another sothat they are not freely rotatable relative to one another but axiallymovable relative to one another, said connecting means including aplurality of splines provided on said parts and engaging with oneanother.
 10. A washer as defined in claim 4; and further comprisingmeans for connecting said parts with one another so that they are notfreely rotatable relative to one another but axially movable relative toone another, said connecting means including means for press fittingsaid parts with one another.
 11. A washer as defined in claim 4; andfurther comprising means for connecting said parts so that they are notfreely rotatable relative to one another but axially movable relative toone another, said connecting means including key means provided betweensaid parts.
 12. A washer as defined in claim 4, wherein at least one ofsaid parts has a non-round surface facing the other of said parts andcooperating with said other part so that said parts are not freelyrotatable relative to one another but axially movable relative to oneanother.
 13. A washer as defined in claim 4, wherein at least one ofsaid parts has a cross-section which cooperates of the other of saidparts so that said parts are not freely rotatable relative to oneanother but axially movable relative to one another.
 14. A washer asdefined in claim 4; and further comprising means for pressing said innerpart toward the thread of the bolt and movable between an inoperativeposition in which it does not press said inner part toward the thread ofthe bolt and an operative position in which it is displaced by anoutside tool toward said inner part so as to press said inner parttoward the thread of the bolt.
 15. A washer as defined in claim 4; andfurther comprising connecting means for connecting said parts with oneanother so that they are not freely rotatable relative to one anotherbut axially movable relative to one another, said connecting meansincluding ring gear means engaging with both said parts.
 16. A washer asdefined in claim 15, wherein said gear means is provided with platemeans adapted to be located between said body and the object.
 17. Awasher as defined in claim 4; and further comprising means forconnecting said parts with one another so that they are not freelyrotatable relative to one another but axially movable relative to oneanother; said connecting means including wedge means provided betweensaid parts.
 18. A washer as defined in claim 1, wherein said secondbearing face surface is formed so as to have a high friction relative tothe object.
 19. A threaded fastener for connecting two parts whichconstitute an object, comprising a bolt having a thread and an axis andintroducable into the parts forming an object; a nut screwable on saidbolt; and a washer to be applied between said nut and said object, saidwasher having an axis and being provided with a first bearing facesurface located at one axial side and adapted to cooperate with saidnut, a second bearing face surface located at an opposite axial side andadapted to cooperate with said object, and at least one third turningresistant surface adapted to cooperate with a bolt with said thread ofsaid bolt, so that when said nut is turned with said given force in onedirection and said washer receives simultaneously said given force in anopposite direction, only said nut turns to tighten or loosen said boltand said washer remains rotation stationary while said bolt elongates orrelaxes in an axial direction.
 20. A method of assembling at least twoparts with one another, comprising the steps of introducing a bolthaving a thread and an axis into the parts so that a free end portion ofthe bolt extends outwardly beyond at least one side of the two parts;placing a friction washer on said free end portion of said bolt so thatsaid friction washer engages with said thread of said bolt to create aturning friction between said washer and said bolt and so as to abutagainst said at least one side of the parts; threadably connecting a nutto said free end portion of said bolt so as to abut against the frictionwasher and to form an assembly; placing a torque power tool on theassembly so as to tighten or loosen the nut with a turning portion ofsaid torque power tool connected to the nut to overcome a threadedfriction with the bolt and a facial friction with the friction washer toturn the nut, and with a reaction portion of the torque power toolconnected to the washer to absorb a reaction force due to a facialfriction of the friction washer with the nut, a facial friction of thewasher with said at least one side of the two parts and a turningfriction with the bolt selected so that the washer does not turn butabsorbs the reaction force of the torque power tool and so that the boltelongates or relaxes in an axial direction.
 21. A washer to be appliedbetween a nut threadingly connected with the bolt which has an axis andis introduced into an object including at least two parts to beassembled, the washer comprising a body having an axis and provided witha first friction area, a first bearing face surface located at one axialside and adapted to cooperate with a nut, a second friction area, asecond bearing face surface located at an opposite axial side andadapted to cooperate with the object, and at least a third frictionarea, a surface adapted to cooperate with a thread of the bolt, so thatwhen the nut is turned with a given torque in one direction the nutturns to tighten or loosen the bolt while said body of the washerremains rotation stationary as the bolt elongates and relaxes.